Management of Tetralogy of Fallot
Complete surgical repair within the first year of life is the definitive treatment for Tetralogy of Fallot, addressing all four anatomic components through VSD closure, RVOT obstruction relief, pulmonary valve management, and extracardiac conduit placement when necessary. 1
Surgical Repair Strategy
Primary complete repair should be performed in the first year of life, including VSD closure and relief of RVOT obstruction through infundibular muscle resection, pulmonary valvotomy, and transannular patch when the pulmonary annulus is inadequate. 1
The transatrial/transpulmonary approach is preferred when feasible to minimize RV injury, though transannular patch is required in approximately 15% of cases when the pulmonary annulus is severely hypoplastic. 2
Coronary anatomy must be defined before any RVOT intervention to avoid interrupting important coronary vessels during surgical repair. 1
Unrepaired TOF in adulthood is associated with significant morbidity and mortality, including polycythemia, thrombotic stroke, pulmonary hypertension, and heart failure. 3, 4
Lifelong Surveillance Requirements
All patients require mandatory annual follow-up with an adult congenital heart disease (ACHD) specialist for life, as pulmonary regurgitation, RV dysfunction, and arrhythmias determine long-term morbidity and mortality. 1
Clinical Assessment Components
Focused history on exercise tolerance, palpitations, dizziness, or syncope at each visit to detect early signs of hemodynamic deterioration or arrhythmias. 1
12-lead ECG to monitor QRS duration—QRS ≥180 ms identifies high risk for sustained ventricular tachycardia and sudden cardiac death, mandating enhanced monitoring. 1
Comprehensive transthoracic echocardiography assessing RV size/function, pulmonary regurgitation severity, residual RVOT obstruction, tricuspid regurgitation, and aortic root dilation. 1
Cardiac MRI for precise RV volume quantification and pulmonary regurgitation assessment, as echocardiography underestimates RV dysfunction. 1
Periodic Holter monitoring with frequency individualized based on hemodynamics and clinical suspicion to detect ventricular arrhythmias. 1
Exercise testing to objectively assess functional capacity and detect exertional arrhythmias. 1
Arrhythmia Management and Sudden Death Prevention
The incidence of sudden death in adult TOF patients is approximately 2.5% per decade, with ventricular tachycardia as the primary mechanism. 1
Symptomatic Patients
Worrisome symptoms (palpitations, dizziness, syncope) mandate immediate evaluation with hemodynamic catheterization and electrophysiology study. 5, 1
Documented sustained ventricular tachycardia or cardiac arrest requires implantable cardioverter defibrillator (ICD) placement. 5, 1
Recurrent sustained monomorphic VT or recurrent ICD shocks can be effectively treated with catheter ablation, though ICD remains necessary due to uncertain recurrence risk after ablation. 1
Asymptomatic Patients with Detected Arrhythmias
Asymptomatic patients with nonsustained VT on surveillance monitoring should undergo electrophysiology study to refine arrhythmia risk, with consideration for surgery if significant pulmonary regurgitation exists. 1
Programmed ventricular stimulation provides reasonably good predictive information regarding the risk of future clinical VT events and all-cause mortality. 5
Beta blockers should be used in patients with frequent or complex ventricular arrhythmias to reduce sudden cardiac arrest risk. 1
Reintervention Criteria
Pulmonary valve replacement (PVR) is the most common reintervention, required in 40-85% of patients 5-10 years after initial repair due to chronic pulmonary regurgitation causing progressive RV dilation and dysfunction. 1, 6
Indications for Intervention
Symptomatic patients with severe pulmonary regurgitation require intervention. 1
Asymptomatic patients with severe pulmonary stenosis or pulmonary regurgitation PLUS progressive or severe RV enlargement or dysfunction require intervention. 1
Residual RVOT obstruction with RV/LV pressure ratio >0.7 or RV systolic pressure >50 mmHg requires intervention. 1
Hemodynamic abnormalities identified during evaluation for arrhythmias, such as residual VSD or significant valve regurgitation, may benefit from surgical intervention combined with intraoperative VT mapping and ablation. 1
Delaying PVR until irreversible RV remodeling occurs worsens outcomes—intervention should occur before this threshold, though determining optimal timing remains challenging. 1, 6
Pregnancy Considerations
Pregnancy is contraindicated in patients with unrepaired TOF. 5, 1
After repair, pregnancy is usually well tolerated if no important hemodynamic residua exist, functional capacity is good, and RV function is no more than mildly depressed with maintained sinus rhythm. 5, 1
Comprehensive cardiovascular evaluation is recommended before each pregnancy, as even severe pulmonary regurgitation is usually tolerated if RV function is preserved and sinus rhythm maintained. 5
Fetal risk: 4-6% risk of congenital heart disease in offspring; screening for 22q11.2 microdeletion should be performed before pregnancy for appropriate genetic counseling. 5, 1
Fetal echocardiography should be offered in the second trimester. 5, 1
Critical Pitfalls to Avoid
Underestimating RV dysfunction even in asymptomatic patients can lead to decompensation under stress or anesthesia. 1
Ignoring QRS duration >180 ms substantially increases arrhythmia risk and should prompt enhanced monitoring and consideration for ICD. 1
Inadequate preoperative assessment without recent echocardiography and knowledge of residual lesions significantly increases risk during non-cardiac surgery. 1
Do not assume repaired TOF patients are "normal"—residual hemodynamic abnormalities are common and affect tolerance to physiologic stress. 7
Never ignore signs of decompensation such as worsening cyanosis, syncope, or palpitations, which mandate immediate evaluation. 7